switched n/w

[kaushal <kaushal () rocsys com>]

Hi,
   Iam a bit new to network securities.We have a switched network and to
my knowledge a hosts' data cannot be sniffed by other host by runnning
tcpdump.But Iam receiving complaints from few users that their data is
being changed/manipulated.Is this possible?
How can I avoid this at the host level?Does this mean the server has
been compromised?Any help or pointer in this aspect would be highly
appreciated.

thanks in advance.

kaushal.